Although sex reversal is fairly common in invertebrates, the presence of male characteristics with a female karyotype in mammals merits a detailed examination.
Four goats of the Toggenburg strain belonging to the Department of Genetics of the Faculdade de Ciencias Medicas e Biologicas of Botucatu, Brasil, with a small vagina, an enlarged penis, a variable degree of labial fusion and a common opening of the urethra and vagina, were found to have a female karyotype. This was established from the chromosomal pattern of cultured leucocytes and sex chromatin studies of brain tissue cells. The same goats were reported to have a male phenotype with a mounting tendency when in the presence of females. Blood samples were taken from these intersex animals and from `normal' males and females to assess testosterone levels. The intersex animals were examined